issues? >> reporter: it's a distinction not lost on either campaign, clinton's camp touting her background. trump's team, his tough talk. >> mr. trump is doing very well on the issue of who would manage islamic radical terrorism. >> i would say experience really matters. >> reporter: still, even the trump campaigns on showing strength, he is under fire for his national security stance from some top republicans, including now two-time defense secretary robert gates, out with a scathing beyond repair. >> robert gates. believe me, i am so much better at what he's doing than he is. >> people say they trust trump on terror, but who better to serve as commander in chief, clinton has the edge. at a time of rising anxiety, a conflicted electorate. national security, of course, one of the top concerns for voters.